8. Hellebore

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While not a weapon in the traditional sense, biological warfare has been massively significant in human history. Over the centuries, diseased people, poisons and, more recently, weaponized anthrax have all been used to attack enemies. But one of the earliest examples of biological warfare was through the use of hellebore, a common plant with poisonous properties. It was used during the siege of Kirrha in 585 B.C., poisoning the water supply and leaving the defenders too weak to withstand attack. The development of this new weapon in warfare has been refined over the centuries and frequently used with devastating effect.

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